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Tidal volume by ideal (predicted) body weight

Study aid only. Not for clinical decisions. This calculator teaches textbook formulas for exam prep. It is not a medical device and does not replace clinical judgment, your facility's protocols, or a licensed clinician's assessment. Nothing you enter leaves your browser.

Formulas

Predicted body weight (PBW), also called ideal body weight on many exams:^[1][2]

• Male: 50 + 2.3 × (height in inches − 60) kg
• Female: 45.5 + 2.3 × (height in inches − 60) kg

Set V_T from PBW, not actual body weight, because lung size follows height and sex. Adults are generally started at 6–8 mL/kg PBW. In ARDS, the guideline recommends 4–8 mL/kg PBW with plateau pressure under 30 cm H₂O.^[1][3] The ARDSNet trial used 6 mL/kg PBW.^[2]

Worked example

Male, 5′10″ (70 in): PBW = 50 + 2.3 × 10 = 73 kg. At 6 mL/kg that's 438 mL; at 8 mL/kg it's 584 mL. Weight on the scale doesn't change these numbers.

Sources

1. NBRC: Setting the Tidal Volume in Adults Receiving Mechanical Ventilation (Bocklage & Balk, 2017, PDF)
2. ARDS Network. Ventilation with lower tidal volumes ... NEJM 2000
3. ATS/ESICM/SCCM 2017 Guideline: Mechanical Ventilation in Adult ARDS (PDF)

Formulas checked against the sources listed above on October 30, 2026. Written and reviewed by a practicing RRT for TidalPrep.